The conventional pliers is generally composed of two jaws which are pivotally coupled such that the two jaws can hold securely a work piece. Such a conventional pliers is defective in design in that the distance between the two jaws can not be adjusted to hold the work pieces of various sizes. Another conventional pliers is composed of two jaws which can be adjusted in distance separating the two jaws for holding the work pieces of various sizes. However, the pivot of the pliers is vulnerable to sliding to result in the poor clamping of the work piece. The pliers disclosed in the U.S. Pat. Nos. 4,651,598 and 4,662,252 are intended to overcome the drawbacks of the conventional pliers described above; nevertheless they can not be easily assembled in view of the embedded biasing spring of the pliers.